Flow pyrometer



Feb. 4, 1930. A. scHAcK ET AL 1,746,012

FLOW PYROMETER Filed July 2, 1927 Patented Feb; 4, 1930 UNITED STATES- PATENT OFFICE SCEACK, OF DUSSELDORF, AND MATHIAS WENZL, OF OBERHAUSEN, GERMANY, 'ASSIGNORS TO SIEMENS &: HALSKE, AKTIENGESELLSCHAFT, F SIEMENSSTADT,

NEAR BERLIN, GERMANY, A CORPORATION OF GERMANY FLOW PYROMETER Application filed July 2 1927, Serial No. 203,030, and in GCLJIHJIY July 8, 1926.

thermo-couples, serious measuring errors arise, particularly in consequence of radiation losses in the transmission of the heat from the gas to the thermo-couple.

With the object of eliminating these errors so called flow pyrometers have already been used in which the thermometer is located within a tube in which a flow of the gas the temperature of which is to be measured is produced by a suction or ejection. Experiments have, however, shown that it is impossible to ascertain the true temperature of the gas with this arrangement. The temperatures indicated by the thermometer within the range of the fire tubes of a steam boiler, for instance, differ from the true gas temperatures of about 900 C. by about 10%.

Even in double-walled flow pyrometers in which the stream of gas is conducted in two concentric streams through the tube housing the thermometer gives very incorrect results. If the flow pyrometer is provided with a strong insulation or lagging the indication is so sluggish that such measuring devices are practically useless.

According to our invention these drawbacks are avoided by surrounding the soldered joint of the thermo-couple or the end of the protective tube or sheath with insertion members which offer a large heating surface to the gas and have a high heat transfer coelficient. v

'An embodiment of our'invention is illustrated in the drawing affixed to this specification and forming part thereof.

The figures of the drawing represent respectively a longitudinal and a transverse section through our improved pyrometer.

Referring to the drawing A is the flow tube for the stream of gas produced by a device adapted to exert suction in the tube, such as a compressed air ejector B. Into the part known as the pyrometer head of the tube A projects the thermo-couple L surrounded by a protective tube or sheath S constructed of a suitable refractory material. The space between the outer tube A and the inner tube S is, particularly in the vicinity of the soldered joint of the thermo-couple L, surround edwith filling members E, such as fine parallel tubes constructed of some suitable refractory material. Th'ese filling members E offer to the gas traversing the tube A a large heating surface and enable a very abundant transfor of heat from the flowing gas to their Walls owing to the narrow channels or ducts penetrating them. In consequence of the very effective heating of the filling members E an undesired exchange of heat between the thermo-couple and the surrounding belt or bundle of filling members is almost entirely avoided. When measuring very high temperatures the heat radiation exchange developing to a particularly high extent iscounteracted by correspondingly increasing the number of fine channels in the filling members E surrounding the tube S.

The filling members E may have the shape of refractory tubes and be arranged in the pyrometer head individually or united into an annular bundle. For certain cases occurring in practical use the pyrometer head or the sheath of the thermo-couple or both of them are preferably made integral with the' filling members of a sufiiciently refractory material. Steatite-magnesia is an example of a suitable material for the filling members E. The space between the sheath S and the tube A may equally well be filled up by an annular filling member of refractory material provided with the necessary fine channels or ducts. When using individual tubes of small diameter as filling members the tubes are preferably placed around the sheath S in a circle or a plurality of concentric circles (see Fig. 2). The large'surface which the filling member or members E offer to contact with the hot gases flowing through the fine channels or ducts,-insures an efiicient absorption of the heat of such gases and a thorough transfer of such heat to the soldered joint of the thermo-couple. The pyrometer head of tube A surrounds all of these channels and acts as ashield to prevent heat losses due to radiation. The walls of the filling memofier a large heating surface to the gas and hers E constitute webs or partitions separathaving high heat conductlng coeificlents ing the several channels or tubes from each In testlmony whereof we aifix our signaother. As stated above, all of these filling tures.

5 members may be made integral with each ALFRED SCI-IACK. other and also, if desired, with the sheath S MATHIAS WENZL. and with the pyrometer head of the tube A.

Various modifications and changes may be made without departing from the spirit and the scope of the invention, and we desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art.

We claim as our invention 15 1. In a flow pyrometer, in combination, a

' flow tube, a thermo-couple with sheath located in said flow tube, and heat-transferring filling members located between said flow tube and said sheath adapted to ofier a large 2 heating surface to the gas. and having high heat conducting coefficients.

2. In a flow pyrometer, in combination, a flow tube, a thermo-couple with sheath located in said fiow tube, and fine tubes located 25 between said flow tube and said sheath adapted to offer a large heating surface to the gas and having high heat conducting coefiicients.

3. In a flow pyrometer, in combination, a 30 flow tube, a thermo-couple with sheath located in said flow tube, and specially shaped rods located between said flow tube and said sheath adapted to offer a lar e heating surface to the gas and having igh heat con- 35 ducting coefficients.

4. In a flow pyrometer, in combination, a flow tube, a thermo-couple with sheath located in said flow tube, and an annular insertion member with fine passages located be- 4o tween said flow tube and said sheath adapted to ofier a large heating surface to the as and having high heat con-ducting coefliclents.

5. In a flow pyrometer, in combination, a flow tube, a thermo-couple with sheath lo- 45 cated in said flow tube, and an annular insertion member with fine passages integral with said flow tube. 1 I 6. In a flow pyrometer, in combination, a

flow tube, a thermo-couple with sheath lo- 50 cated in said flow tube, and an annular insertion member with fine passages integral with said sheath.

7. In a flow pyrometer, in combination, a flow tube, a thermo-couple with sheath 10-. 55 cated in said flow tube, and insertion members located between said flow tubeand said sheath adapted to offer a large heating surface to the gas and having high heat conducting coefficients, said flow tube, sheath and insertion members being constructed in one piece.

8. In a flow pyrometer, in combination, a flow tube, a thermo-couple with sheath located in said flow tube, and webs located between said tube and said sheath adapted to 

